Reporting tools like Cognos and BusinessObjects use the concept of "semantic layer" with projects (Cognos) and universes (B/O).

Does Pentaho Reporting have a semantic layer too? If so, can someone please give a few pointers about it?

Thanks in advance for your help. I hope I am posting in the correct forum.

Taqua

01-13-2009, 01:35 PM

Hehe, me again. :) Pentaho Metadata *is* the semantic layer.

The metadata layer acts as a abstraction layer shielding the common users from the ugliness of SQL or technical details of your data storage. And on top of that, it is the place to enrich your model with semantic metadata (for which we borrowed concepts from the "Semantic-network" world; so you can model your world with concepts and relations).

Pentaho Reporting (and other tools using the metadata layer) then uses that metadata layer to (1) present your users a simple and easy to use view on your data, delegating the task of creating joins or other complex low-level stuff to the metadata engine itself and (2) providing additional hints about your data, ranging from better names to formatting information (this number always with 2 decimals, that one with a currency symbol please) to any other additional data you want to put in.

For the current Platform 1.7/2.0 systems, the reporting to metadata integration is fairly simple and concentrates almost exclusively on the data-access problem. Real integration, including the ability to use the markup of the metadata layer in the reports and custom report-functions (beyond what is already predefined) is part of the next reporting release.

For an Overview about what you can do, the Metadata Editor documentation is a good place to start:
http://wiki.pentaho.com/display/ServerDoc2x/Pentaho+Metadata+Editor

acbonnemaison

01-13-2009, 02:38 PM

Hehe, me again. :) Pentaho Metadata *is* the semantic layer.

The metadata layer acts as a abstraction layer shielding the common users from the ugliness of SQL or technical details of your data storage. And on top of that, it is the place to enrich your model with semantic metadata (for which we borrowed concepts from the "Semantic-network" world; so you can model your world with concepts and relations).

Pentaho Reporting (and other tools using the metadata layer) then uses that metadata layer to (1) present your users a simple and easy to use view on your data, delegating the task of creating joins or other complex low-level stuff to the metadata engine itself and (2) providing additional hints about your data, ranging from better names to formatting information (this number always with 2 decimals, that one with a currency symbol please) to any other additional data you want to put in.

For the current Platform 1.7/2.0 systems, the reporting to metadata integration is fairly simple and concentrates almost exclusively on the data-access problem. Real integration, including the ability to use the markup of the metadata layer in the reports and custom report-functions (beyond what is already predefined) is part of the next reporting release.

For an Overview about what you can do, the Metadata Editor documentation is a good place to start:
http://wiki.pentaho.com/display/ServerDoc2x/Pentaho+Metadata+Editor